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doubleoboyle's profile

Contributor

 • 

2 Messages

Saturday, July 25th, 2015 3:16 AM

cascaded network unable to access default gateway att 5031nv

Hello - 

 

I have a Cisco 3750 sitting behind an ATT 5031 NV.  The Cisco device has the following networks 'living' on it:

 

10.1.1.1 /24

10.1.2.1 /24

10.1.3.1 /24

 

All of these have DHCP pools living on the Cisco device.  The default gateway they had out is the IP of the SVI (mentioned above).  I am using OSPF between those networks - and they can all talk fine.  I am using the 'default-information originate' command to obtain default route information.

 

I have port Gi1/0/3 on the cisco device plugged into LAN port 4 on the ATT 5031 NV.  Port Gi 1/0/3 is configured with a static IP in the 192.168.1.x network as follows:

ip address 192.168.1.2 255.255.255.0

 

On the ATT 5031 NV:  Settings > broadband > link configuration, I have the 'cascaded network' option selected:

 

Network Address:  10.1.0.0 

Subnet Mask:  255.255.0.0

 

Choose the router that will host the secondary subnet:  

        [Cisco Device Hostname] 192.168.1.2 (IP of Gi1/0/3 on cisco device)

 

When i do this - i can ping from the 10.x.x.x networks to both 192.168.1.2 and 192.168.1.254 IP's - but i cannot get out to the Internet (neither by IP or hostname).  

 

I should metion that I have tried the DMZ pinhole option - where i made my Gi1/0/3 get an IP by DHCP > rebooted it > and I got my device to show up with a 108.225.x.x external IP (which again, my 10.x.x.x's could ping) but I could not ping the default gateway for that network.

 

What am i missing here?  anyone have any ideas?  Config to follow:

 

 

!

interface GigabitEthernet1/0/3
description DMZ to WAN
no switchport
ip address 192.168.1.2 255.255.255.0

!interface Vlan1
no ip address
!
interface Vlan100
description MANAGEMENT
ip address 10.1.1.1 255.255.255.0
!
interface Vlan120
description xxxx WIFI
ip address 10.1.2.1 255.255.255.0
!
interface Vlan130
description xxxx DATA
ip address 10.1.3.1 255.255.255.0

!

router ospf 1
network 10.1.1.0 0.0.0.255 area 1
network 10.1.2.0 0.0.0.255 area 1
network 10.1.3.0 0.0.0.255 area 1
default-information originate

!

ip default-gateway 192.168.1.254

!

ip route 0.0.0.0 0.0.0.0 192.168.1.254

 

Any help would be greatly appricated.  

 

 

 

Community Support

 • 

6.7K Messages

8 years ago

Hi @doubleoboyle,

 

With the cascaded router option, the purpose of that option is to pass over your static IPs so that your gateway handles the traffic. If you do have a set of static IPs available, the only thing you want to change is the cascaded router IP. The network address should be the IP of your router, so it would be 192.168.1.2 according to your setup. 

 

If you are just trying to do a router behind router setup, you actually do not need to use the cascaded router option, and just putting it in DMZ should take care of everything.

 

Hope this helps.

 

-ATTU-verseCare

Contributor

 • 

2 Messages

8 years ago

Thanks for the quick response!

 

I actually did do the DMZ pinhole option where my Gi1/0/3 obtained the external 108.225.x.x IP - and I was still unable to ping the default gateway for the 108.225.x.x network.  All of my internal networks could ping the IP of my Gi1/0/3.

 

If i do that DMZ pinhole option, is NAT required on the secondary router for the 10.x.x.x networks if I do'nt have a bunch of static IP's allocated by ATT?

 

With the cascaded router option i was able to ping out to the Internet from my Cisco device (because it was leaving on the gi1/0/3 interface which was on the 192.168.x.x network hosted by the ATT cable modem).

Community Support

 • 

6.7K Messages

8 years ago

Hi,

 

I would think you would want to assign the static IPs to your interfaces and if you want to create a NAT, you can create a DHCP pool for each interface. If you do not have static IPs with AT&T, you definitely want to create the NAT, but you may not be able to use the class A private IP addresses, as the U-verse gateway does not route those. If you do wish to use them, you would have to create a double NAT.

 

Hope this helps.

 

-ATTU-verseCare

Contributor

 • 

1 Message

7 years ago

Why is everywhere (http://192.168.1.2 or 192.168.0.1 or 192.168.1.1) ?

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